MDX 101 Getting Multi-Dimensional

Transcription

1 MDX 101 Getting Multi-Dimensional Alex Whittles PurpleFrogSystems.com Slides:

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3 Alex Whittles SQL Relay ExCo SQLRelay.co.uk SQL Bits Committee SQLBits.com Birmingham SQL UG SQLMidlands.com Birmingham Azure UG AzureBirmingham.uk MSc in Business Intelligence, CEng, CITP, FBCS, FIOEE, MIET, MIOD Run BI Consultancy Business Intelligence Consultancy Data Modelling Data Warehousing OLAP Cubes ETL Systems Reporting Systems Managed Service

4 What is MDX? Query Language Used to query OLAP Cubes Love child of SQL and a Rubik s Cube

5 SQL vs MDX SELECT CurrencyName, OrderDateKey, OrderQuantity FROM FactInternetSales fis INNER JOIN dbo.dimcurrency dc ON fis.currencykey = dc.currencykey

6 SQL vs MDX SELECT [Currency].[Currency].MEMBERS ON COLUMNS, [Date].[Calendar].[Year].MEMBERS ON ROWS FROM [Adventure Works] WHERE [Measures].[Internet Order Count]

7 Cube Basics SSIS Integration Services SQL Server SSRS Reporting Services SSAS Analysis Services Query using: Excel SSRS PerformancePoint MDX Other tools

8 Cube Basics Reports Cube Data Warehouse Finance Database Sales Database Marketing XLS 3 rd Party CSV

9 Cube Benefits Speed Simplicity Business Calculation Logic Drag & Drop Power of MDX

10 Dimensions Vs Measures Dimensions Usually text Things you group or filter by A number of attributes Measures Always numbers Things you add up

11 The Star Schema Dimension Dimension Measures Dimension Dimension

12 MDX Basics Query Structure SELECT { SET } ON COLUMNS, { SET } ON ROWS FROM CUBE WHERE ( TUPLE )

13 MDX Basics Query Example SELECT { [Date].[Calendar Year].MEMBERS } ON COLUMNS, { [Product].[Category].MEMBERS } ON ROWS FROM [Adventure Works] WHERE ( [Measures].[Internet Sales Amount] )

14 MDX Basics Cheat Sheet Member Tuple Set Set MDX SQL Equivalent (ish) Syntax Measure Column (numeric) [Measures].[xxx] Dimension Table [Dimension] Attribute Column (text) [Dimension].[Attribute] Hierarchy GROUP BY Col1, Col2 [Dimension].[Hierarchy] Member Row [Dimension].[Attribute].[Member] [Dimension].[Hierarchy].[Member] Tuple Multiple WHEREs ( Member, Member, Member, ) Set Union { Member, Member, Member, } { Tuple, Tuple, Tuple, }

15 Cube Basics - Dimensions Dimension A denormalised business entity Customer / Product / Date / Employee / etc. Sourced from a SQL Server table in the data warehouse Cubes Dimension Attribute Member SQL Equivalent Table Column Row

16 Cube Basics - Members Member A single item from a dimension attribute e.g. a Date, a Year, a product, an employee Set Multiple members OF THE SAME attribute e.g. Today & Yesterday or Customer IDs 123, 2921 and 5234

17 Cube Basics - Members

18 Syntax - Members [Dimension].[Attribute].[Member] [Date].[Year].[2013] [Date].[Date].[ ] [Customer].[Customer].[Waitrose] [Customer].[Country].[UK] [Date].[Year].CURRENTMEMBER

19 Syntax Member Keys [Dimension].[Attribute].&[Member] [Date].[Year].[2013] [Date].[Year].&[2013] [Date].[Month].[March] [Date].[Month].&[3] (Name) (Key) (Name) (Key)

20 Cube Basics - Sets

21 Syntax - Sets { MEMBER1, MEMBER2, MEMBER3 } { [Date].[Year].[2010], [Date].[Year].[2012] } { [Date].[Year].[2010] : [Date].[Year].[2012] } { null : [Date].[Year].CURRENTMEMBER }

22 Cube Basics - Tuples

23 Syntax - Tuples ( MEMBER, MEMBER, ) ([Date].[Year].[2012], [Customer].[Customer].[Waitrose]) ([Date].[Year].[2012], [Customer].[Customer].[Waitrose], [Product].[Product].[Banana])

24 Cube Basics Tuples revisited!

25 Cube Basics Tuples revisited!

26 Cube Basics Sets revisited!

27 Syntax - Sets { MEMBER1, MEMBER2, } { (TUPLE1), (TUPLE2), } { ([Date].[Year].[2010], [Product].[Product].[Banana]), ( [Date].[Year].[2012], [Product].[Product].[Apple] ) }

28 Demo Basic Queries SELECT xxx ON COLUMNS SELECT xxx ON ROWS MEMBERS TUPLES SETS Basic Calculations

29 Demo

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44 Demo

45 Dimension Navigation CURRENTMEMBER The query has context The current member relevant in the query [Date].[Year].CURRENTMEMBER PREVMEMBER The one before to the current member [Date].[Year].PREVMEMBER

46 Relative Calculations Change since previous year [Date].[Year].CURRENTMEMBER - [Date].[Year].PREVMEMBER

47 Hierarchies Year Product Type Month Product Group Date Product Product Version

48 Parent Child Hierarchies Top Dog Manager Employee Employee Employee Employee Employee

49 Dimension Navigation DESCENDANTS ANCESTORS PARENT CHILDREN SIBLINGS

50 Demo Dimension Navigation Dimension Navigation DESCENDANTS ANCESTORS PARENT CHILDREN SIBLINGS

51 Demo

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59 Visualising Queries Very different to SQL Think in blocks E.g. All data EXCEPT for xxx Two calculations and subtract them minus

60 MDX Summary Think in MDX, don t translate from SQL Member / Set / Tuple Write generic queries Use navigation functions Use MDX for what it s good at

61 MDX Where Next? Technitrain.com MDX Studio

62 MDX Slides: